As hope builds over possible frequent at-home testing, experts call the idea a long shot.

Over the past few weeks, a Harvard scientist has made headlines for a bold idea to curb the spread of the coronavirus: rolling out antigen tests, a decades-old underdog in testing technology, to tens of millions of Americans for near-daily, at-home use.

WASHINGTON — Chinese intelligence hackers were intent on stealing coronavirus vaccine data, so they looked for what they believed would be an easy target. Instead of simply going after pharmaceutical companies, they conducted digital reconnaissance on the University of North Carolina and other schools doing cutting-edge research.

A group of drug companies competing with one another to be among the first to develop coronavirus vaccines are planning to pledge early next week that they will not release any vaccines that do not follow rigorous efficacy and safety standards, according to representatives of three of the companies.

As the United States withdraws from membership in the World Health Organization, the Trump administration will redirect $62 million still owed for this year’s dues to other health-related causes also under United Nations auspices, State Department officials announced on Wednesday.

Most of the redirected money will go to children’s immunization and influenza surveillance, officials said. But the United States Agency for International Development will continue with plans to give $68 million to the W.H.O. to support its work in Libya and Syria, and on polio eradication in Pakistan and Afghanistan.